Blood!!

I am so scared. On a Saturday night I had sex with my boyfriend for the first time without using protection. Today being a Tuesday I took the morning after pill prescribed by my doctor. I am really scared that I could be pregnant. When I urinate it is a red-ish colour at first. Can someone please tell me if this is blood? I am also in a lot of pain when I go to the toilet, I know this is a weird thing to say but someone please help!!!! xx